Rotary forging has been conventionally known as a technique for hot-forging a disk-shaped material to be forged. For example, JP 2009-012059 A discloses a method in which a rotary forging apparatus including upper and lower dies is used, the apparatus holds a material to be forged on top and bottom surfaces of the material and presses the material to perform forging, the upper die is then separated and rotated, the upper die is then pressed onto the top surface of the material to be forged again, and the above series of operations is repeated to perform hot forging.